Improvement in cylindrical steam-boilers



v W. TUCKER. Cylindrical Steam-Boiler,

No. 208,868. Patented Oct. 8,1878.

N4 PETERS, PHOTU-LIFHOBRAFHER, WASHINGTON O C UNITED STATES PATENTOEEIoE.

"WILLIAM TUCKER, OF EAST BROOKFIELD, MASSACHUSETTS.

IMPROVEMENT IN CYLINDRICAL STEAM-BOILERS.

Specification forming part of Letters Patent No. 208,868, dated October8, 1878; application filed May 1, 1878.

To all whom it may concern:

Be it known that I, WILLIAM TUcKER, of East Brookfield, in the county ofWorcester, Massachusetts, have invented a new and useful Improvement inthe Construction of Oylindrical Steam-Boilers, of which the followin gis a full, clear, and exact specification.

My present invention relates exclusively to the construction of theshells of cylindrical (fire-flue) boilers, the prime object being togive such shells the maximum of strength with reduced cost.

Mysaid invention consists, first, in constructing the sides of suchboiler-shells of iron or steel rolled endlessly into rings or seamlessbands of the required diameter, and of about the thickness of ordinaryboiler-iron for a given shell. The ends or edges of said rings beingadapted to form the circumferential seams of the shell, with or withoutthe aid of rivets at said circumferential seams, I thus avoid the weaklongitudinal joints of ordinary boiler-shells, and utilize the fullstrength of the metal to resist the severe transverse or radial strainin high-pressure boilers.

My said invention consists, secondly, in a rivetless shell forcylindrical boilers, composed of one or more endless bands or rings ofrolled iron or steel and a pair of flue-sheets, united by means ofscrew-joints of one or more circumferential threads each, so as to doaway with the noisy, tedious, and more expensive work of riveting, ashereinafter more fully set forth.

Figure 1 of the accompanying drawing is a perspective view of the shellof a cylindrical multi-flue boiler, illustrating this invention. Fig. 2is a vertical longitudinal section of the same on a larger scale. Fig. 3is a transverse section on the line 3 3, Fig. 2. Fig. 4is averticallongitudinal section of one end of anotherboiler shell; and Fig. 5 is anelevation of one end of another, illustrating certain modifications.

Like letters of reference indicate corresponding parts in the severalfigures.

The improved shell for cylindrical boilers shown in Figs. 1,2, 3 is madewithout the usual noisy and tedious work of riveting, and is greatlysuperior to riveted shells as regards cheapness and strength.

A sufficient number of endless bands or rings, A A A united end to end,constitute the cylindrical sides of the shell, and a pair offlue-sheets, B B, constitute the ends or heads.

The endless bands or rings A A A which may be of different widths, arepreferably cast in smaller and thicker rings of steel and rolledendlessly until they come to the required thicknessand diameter. Theymay also be welded of iron or steel and rolled in the same way.

In the illustration threevarieties of the end- 7 less bands, as regardsdetail, are represented. Two bands, A, are perfectly plain, except anenlargement, 2, rolled at one edge of each, and screw-threadedinternally, and a matching ex ternal thread, at the opposite edge ofeach. The second pattern, A is like the first as regards its edges orends, and has a vertical neck, as, to receive a steam-dome. This neckmay be formed in one part with the band, after the rolling of the latteris finished, by perforatin g and striking up the band at this pointbeneath a steam-hammer or the steam-dome may be otherwise attached. Itwould only be required, of course, in horizontal boilers. The smallerattachments maybe tapped in as usual, and the man-hole and other similaropenings may be formed in any approved manner. The third pattern ofband, A is externally threaded at both ends or edges, being the terminalband.

The flue-sheets B B will be made of the same metal as the endless bands,and may be rolled or hammered, being preferably made seamless, withinternally-threaded flanges z corresponding with the internally threadedends 2 of the endless bands.

The screw-threaded ends will be cut in a suitable lathe, and be madeslightly tapering, and the parts will be screwed together by means ofhydraulic jacks, the said taper insuring the formation of steam-tightjoints before the ends of the sections come together, so as to leaveinternal spaces to in the joints.

The entire absence of longitudinal joints is the feature of primeimportance in this invention. A single riveted boiler, owing to thepunching out of so large a percentage of the plate for rivet-holes, hasonly fifty per centum of the strength of the plate at its joints, andthe best double-riveted seams are allowed but seventy per cent. of thestrength of the plate.

This strength is sufii cientfor the circumferential joints, as thestrain on these joints-that is, the longitudinal strain on the shell-isto the transverse or radial strain, which tends to make the longitudinaltear, as 1 is to 2. Consequently, by the absence of longitudinal jointsin the improved shell, it is insured one hundred per eentum of the fullstrength of whole stock, as compared to seventy per cent. in the bestdouble-riveted boilers of ordinary make, and one hundred per cent. ascompared to fifty per cent. in the common sin gle-riveted boilers, whilethe improved boiler-shell can be built at a lower cost.

In said Figs. 1, 2, 3 the flue-sheets B B are shown perforated toreceive small flue-tubes.

The modifications illustrated in Fig. 4 consist, first, in the piercingof the flne'sheets for one or more large fines; and, secondly, in theemployment of independent steel couplingrings 0, with right and leftinternal screwthreads, in combination with endless bands A andfine-sheets B screw-threaded externally to receive said coupling rings.The adoption of this form of joint would facilitate rolling the metal,and would facilitate the expansion of the socket parts by heatpreliminary to making the joints should this be de sirable.

Fig. 5 illustrates the employment of rivets r in lieu of screw-couplingsfor uniting endless bands or rings A and heads B The endless bands inthis modification are made very slightly conical, so as to be joined endto end by entering one a little into another.

Perfectly cylindrical bands of different diam-' ters may be employed, ifpreferred, and, although single-riveting is considered sufiicient foruniting the endless bands,two rows of rivets at each joint may, ofcourse, be employed, if preferred. The rivetholes in the endless bandsor rings and in the flanges of the heads may he made by drilling orpunching the same indexically in a dial-machine, as gears are cut, andcan thus readily be made to agree mathematically, as the shape of thestock is not subsequently changed. v

For some uses the improved boiler-shell may consist of a single endlessband or ring united to a pair of flue-sheets or their equivalent byeither screw-joints or rivets.

This invention is not confined to horizontal boilers, nor to anyparticular system of fiues, but may be embodied in any cylindrical(firefiue) boiler, the flue-sheets and the terminations of the shell tobe modified 'as circumstances may demand.

I am aware that it is common to construct tubnlous boilers wholly ofdrawn tubes, with plugs or caps. In this case there is no shell,properly speaking, and the application of this mode of building to theshells of cylindrical boilers has never been proposed, I think, andwould be utterly impracticable.

I am also aware that it has been proposed to strengthenshells ofordinary boiler iron by means of welded rings secured between thesuccessive lengths, and do not wish to be understood as claiming anysuch arrangement.

The following is what I claim as new and of my own invention, and desireto secure by Letters Patent, namely:

1. A cylindrical boilershell composed of endless bands or rings of ironor steel, rolled endlessly, and adapted at their ends or edges toformthe circumferential seams of the boiler-shell, as herein specified,for the purpose of utilizing the full strength of the metal inresistance to radial strain.

2. A rivet-less shell for cylindrical (fire-flue) boilers composed ofoneor more endless bands or rings of rolled iron or steel and a pair offlue-sheets, united by means of scrcw joints of one or morecircumferential threads each, substantially as herein shown anddescribed, for the purposes set forth.

VILLIAM TUCKER.

YVitnesses:

ARTEMAS l3. BABBITT, JosrAn Horns.

